Certain flag emojis appear cut off in PDF

**Describe the bug**
Certain flag emojis display cut off with a green top border.

**To Reproduce**

1. Visit the emoji example Repl (https://react-pdf.org/repl?example=emoji) or set up a local react-pdf implementation
2. Register an emoji source using the URL provided in the documentation (https://twemoji.maxcdn.com/2/72x72/)
3. Add an emoji for the flag for France, Italy, or Greece to a page in the PDF document, wrapped in ``

**Expected behavior**
Flag emojis display consistently, at full size.

**Screenshots**

Here is an example of the bug occurring in the Repl. Only certain flags have this problem. Unsure if this is a Twemoji issue or a React-Pdf issue, but the Twemoji example HTML file does not show this version of those flags.

**Desktop (please complete the following information):**
- MacOS Mojave
- Browser: Chrome 85.0.4183.121, Firefox 81.0.1
- React-PDF 1.6.10